At present, electronic cigarettes include key electronic cigarettes or air-switch electronic cigarettes. The keys may be disabled or stuck after long-term use due to limited number of times or man-made damage. When put in clothes, electronic cigarettes may work sometimes if the keys are pressed unconsciously, so there is a certain issue of safety. In operation, it is required to press and hold the keys hard to enable the electronic cigarettes to work.
The rise of capacitive touch technology brings great convenience for people's production and life. Capacitive touch technology refers to that touch detection is performed in a number of lattice points intersected horizontally and vertically and then charge levels at contact points are detected, so that it is determined whether a finger touches a sensing surface by monitoring the small change in capacitance and then information about the position of a touch point is acquired by detecting the change rule of capacitance of the lattice points.
From the composition of capacitive lattice points, capacitive touch includes self-capacitive touch and mutual-capacitive touch.
The structural principle of mutual-capacitive touch is shown in FIG. 5 and FIG. 6. Capacitive lattice points are formed of longitudinal sensing lines and transverse drive lines. The point of intersection of the two lines has mutual capacitance. If a finger of a person approaches to this point, the electric field lines of a part of mutual capacitance will be absorbed because the human body may be equivalent to a potential; equivalently, the mutual capacitance is reduced. If the capacitance of each of the lattice points is scanned continuously, the position touched by a person may be acquired. The mutual capacitance may be formed on a plane, that is, capacitive lattice points may realize mutual-inductance on a single plane, as shown in FIG. 7.
The structural principle of self-capacitive touch is shown in FIG. 8. As the human body may be equivalent to a fixed potential, when the human body gets close to a sensing line, the capacitance of the sensing line to the ground (the human body may be regarded as the ground) will increase, that is, the self-capacitance thereof increases. For example, when a point (X1, Y2) is touched, the capacitances of X1 and Y2 become larger, and therefore the touch position may be determined. By continuously scanning the capacitance of each line to the ground (or a certain fixed potential), a touch coordinate may be determined. However, on an electronic cigarette, the area of a capacitive touch portion is pretty small, and this demand is extremely urgent particularly with a technical development trend of small but excellent at present. It is required to calculate capacitance by software and finally fit it with the structure of the electronic cigarettes to achieve the best touch effect.